Knitting

I realize I'm probably opening up a whole kettle of fish by asking this, but I am new to knitting and wonder whether it's worth it to bother buying stitch markers. Right now I'm just using a loop of a contrasting scrap yarn as a stitch marker. It can be a little cumbersome, but I don't have to worry about losing it (can always get more small bits of yarn). Annoyingly, the acrylic yarns tend to fray a bit.

I've read that it's much smoother and faster to use the commercially made stitch markers, but I do wonder (a) if that is just slick marketing, (b) about the wasted plastic/shipping/processing costs to the environment, (c) about what happens when I lose the expensive little things.

Thoughts?

UPDATE: Thanks for all the suggestions and input, folks! I think I will go crazy if I try to respond to every reply, so I'll just say thanks here!